Method for determining an interior temperature of a passenger area of a motor vehicle, arrangement for execution of the method, and a temperature sensor

ABSTRACT

A signal (S normal ) is provided to a heat element of a temperature sensor, which is recorded as a step response (L ruh , L bew ). From the difference of the step response compared with the reaction adaptively determined with the temperature sensor at zero air circulation, air flow or no air flow is determined.

This nonprovisional application claims priority under 35 U.S.C. § 119(a)on German Patent Application No. 103 02 285.6 filed in Germany on Jan.22, 2003, which is herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method, an arrangement, and atemperature sensor in order to make a determination of the interiortemperature of a vehicle, taking into consideration changing heattransmission resistance of a control element surface to the surroundingair flow.

2. Description of the Background Art

To automatically regulate the interior temperature in a motor vehicle itis necessary to know the actual interior temperature at a particulartime point. As a rule, a control value is determined, which reflects thedeviation of the actual interior temperature from the desired interiortemperature. The control value serves to regulate the difference. Such amethod is described in DE 40 24 431 A1, which is incorporated herein byreference.

In DE 198 29 143 C1, which is incorporated herein by reference, afurther method for changing the interior temperature of a vehicle isdisclosed. To compensate for changes in the actual value of the interiortemperature due to exterior influences, for example low exteriortemperature, an interior temperature-sensing element as well as anexterior sensor are provided. The interior temperature-sensing elementis located in a control unit.

DE 197 28 803 C1, which is incorporated herein by reference, disclosesan arrangement for measuring and/or regulating temperature with ahousing, inside of which is a temperature-sensing element for measuringthe interior temperature outside of the housing, whereby one or severalheat sources are present inside and/or on the housing. Additionally, atleast one auxiliary temperature-sensing element is provided inside thehousing at an area where the temperature is more intensely influenced bythe heat flow from the heat source than is the temperature at thetemperature-sensing element.

A disadvantage of the solution just described is the big deviation ofthe measured temperature signals from the actual interior temperaturedue to the large amount of interferences with the sensor as well as thegreat inertness of the sensor, which detects changes in the interiortemperature with a time delay and smoothed. Therefore, considerableeffort to correct the temperature signals is required.

From DE 100 16 419 C2, which is incorporated herein by reference, adevice for indirectly recording incident sun radiation in the interiorof a vehicle is known. The photo sensor used is attached to a housing insuch a way that it is not exposed directly to incident sun radiationand, therefore, only measures the radiation of the sun that is reflectedand/or transmitted into the interior of the vehicle.

Presently, measuring methods are being developed, which measure theinterior temperature directly on the surface of a control elementwithout forced air circulation using a NTC (resistor with a negativetemperature coefficient), e.g., a NTC thermistor. The unreliability ofthis measuring method is a result of the varying air circulation on thesurface of the control element, which greatly relativizes themeasurement values at the NTC, even when taking self-heating and theinfluence of the sun into consideration.

From DE 100 49 979 C2, which is incorporated herein by reference, adevice for determining the temperature in the interior of a vehicle isknown, whereby the temperature-sensing element is arranged behind a walladjoining the interior. A heat-conducting element is provided to recordthe air temperature of the interior within the area close to its walls.The heat-conducting element is in heat conductivity contact with atemperature-sensing element and is attached to and/or close to the wallor in an opening in the wall. With this device, interference frompartial sun radiation on the sensor housing is recorded and correctedaccordingly.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a method,an arrangement, and a temperature sensor in order to make a satisfactorydetermination of the interior temperature of, for example, a vehiclepossible, taking into consideration changing heat transmissionresistance of a control element surface to the surrounding air flow.

The invention is based on the knowledge that, for example in the case ofincident sun radiation, a sensor measuring this radiation is heated upmore without air circulation than with air circulation. The same effectoccurs when measuring the temperature of the control element surface dueto self-heating of the electronics. Here, too, measuring results arealtered by air circulation. This air circulation in an interior of avehicle can be produced by, for example, an operation of a heating andair-conditioning system of a vehicle or by the opening of a window whilethe vehicle is traveling.

To eliminate these alterations from the measuring results, the presenceof moving or still air at a measuring area is determined, that is, theintensity of air circulation is determined. This information is weightedand is entered as a correction value into a control value of a settingin order to acquire an interior temperature of a vehicle, taking intoconsideration the heat transmission resistance of the control elementsurface to the surrounding air flow.

An important factor when putting this idea into practice is theconfiguration of the components to one another, in order to be able todetermine the influence of air at the measurement area. Therefore, aheat element is directly temperature-coupled to a sensor, which,preferably, determines the temperature of the control element surface.The sensor is slightly heated with short pulses in relatively long timeintervals by a heat element. From the difference of the step response incomparison with a reaction adaptively observed by the sensor at no aircirculation, the influence of air flow can be determined and theinterference values “warming of the control element” and in particular“sun” can be weighted. The correction signal resulting from theweighting is entered into the calculation of the control setting and theadjustment.

In a preferred embodiment, both components are integrated in a sensorhousing, which is attached as an Incar-sensor on the surface of atemperature control element. The temperature sensor for the controlelement surface and the heat element are attached to a foil in thehousing, which accomplishes the desired temperature coupling of bothcomponents. Furthermore, the sensor has an impulse-damping segmentbetween the two components, which is formed by the foil and conductingtracks.

With the aid of the Incar-sensor thus constructed, the changing heattransmission resistances of the control element surface to thesurrounding air flow can be directly determined.

In a further preferred embodiment, the Incar-sensor has, additionally oralternatively, to the heat element and the NTC, a solar, e.g., alight-sensitive sensor, which is used to determine incident sunradiation at the measuring area.

If, in addition, the self-heating of the control elements is to be takeninto consideration, the NTC, which is preferably located in theregulating system, that is, in the control element electronics, can beused for measuring, whereby the integration of a further, separate NTCinto the Incar-sensor is possible.

It is preferred that the Incar-sensor, e.g., temperature sensor, ismanufactured using foil injection technology (the back of the foil isinjection molded with synthetic materials) or MID (Molded InterconnectDevices) technology.

By using the Incar-sensor, a sensor ventilator is no longer needed,which eliminates known disadvantages like dirt accumulation and noise.Furthermore, it offers new possibilities for the design and constructionof control elements.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus, are not limitiveof the present invention, and wherein:

FIGS. 1 a–c show the construction of an Incar-sensor using MIDtechnology;

FIG. 2 a is a top view of an Incar-sensor produced with foil technology;

FIG. 2 b is a sectional view II–IIb of the sensor of FIG. 2;

FIG. 2 c is the foil of FIG. 2 b in a top view;

FIG. 3 is a top view of a control element with an Incar-sensor;

FIG. 4 is an impulse diagram to illustrate the impact of aircirculation; and

FIG. 5 is a diagram illustrating the skipping of the air temperature ata measuring area.

DETAILED DESCRIPTION

In FIGS. 1 a–c, a compact sensor 1, produced with MID technology, isillustrated in various views as an Incar-sensor or a temperature sensor.FIG. 1 a shows the sensor in a front view, FIG. 1 b in a side view, andFIG. 1 c in a top view, each of which are cross-sectional views.

Sensor 1 has a housing 2, which in its top part has, for example, a foil3, which functions as a substrate of the sensor 1. Towards its bottom,the housing 2 can be closed off with a casting compound 4. On foil 3, ina preferred embodiment, a heat element 5, for example a heat resistor, asolar sensor 6, for example a photo sensor, as well as a NTC element 7are provided and are attached from the rear. The foil 3 is made of PC(polycarbonate) or macrolon, for example. On the foil 3, located betweenthe heat element 5 and the NTC 7, there are copper or silver tracks tocreate an impulse damping segment 8. In the housing 2, between the foil3 and the components 5, 6, 7, and the casting compound 4, there is aheat insulation material 9, which also can be air, among other things.As illustrated in FIG. 1 b in more detail, the electrical contact to asignal processing unit (not shown in detail) is made via contact pins10. FIG. 1 c illustrates the contact pins 10, which in turn are inelectrical contact with the individual components 5–7 via conductingtracks 11.

FIG. 2 a shows a top view of an Incar-sensor 20 made with foiltechnology. The sensor 20 illustrated therein preferably has a housing21 with outer dimensions of, for example, 17×8×3 mm.

FIG. 2 b shows the sensor 20 of FIG. 2 a in cross section IIb—IIb. Thisembodiment also has a heat element 22, an impulse-damping segment 23,and a NTC-element 24 integrated in a mutual housing 21 and a foil 25being attached to the rear. The exceptional flexibility of the foil 25allows a folding and/or bending of the foil 25 within the sensor housing21. Through the folding of the foil 25, chambers are thus created.

Furthermore, in a preferred embodiment, the sensor 20 has alight-sensitive sensor 28, for example a photo sensor. The foil 25 ispreferably IR (infrared) permeable, at least in the area of the photosensor 28 that is located below the foil 25. A foil track 26 with a zerooutput plug 27 serves as contact to an evaluation unit (not shown indetail). It is also beneficial to attach an additional NTC 29 within thesensor housing 21. It can be used to determine the self-heating of thecontrol element. The housing 21 is open at this area for this verypurpose. Preferably, the housing 21 is constructed of multiple parts,which can be snapped together via, for example, latching projections.

Preferably, the sensor 20 is constructed as follows:

The heat element 22 is directly attached to the foil 25 using thick filmtechnology. The NTC 24 can then be either glued with conductive adhesiveor soldered to the foil 25. The heat guide, e.g., impulse dampingsegment 23, is attached directly to the foil 25. As previouslymentioned, the foil 25 can be made of polycarbonate or polyimide etc.,which, preferably, has IR (infrared) light permeable areas. The foil 25is then put into the sensor housing 21, preferably with adhesive and/orby injection molding. If the foil 25 is not made of IR-light permeablematerial, the foil 25 can alternatively be covered or replaced with anIR-light permeable varnish, either entirely or partially, but at leastin the area of the photo sensor 28.

FIG. 3 is an illustration of a control element 30 in the interior of amotor vehicle (not shown in detail). Also illustrated is an NTC 31 thatis located in the control element 30, and which can be used to determinethe self-heating of the control element.

With the compact temperature sensor 1, 20, its upper part areaing to theinterior, and with the aid of the solar sensor 6 and/or thelight-sensitive sensor 28, the incident sun radiation at the measuringarea/contact element 30 can be measured in a conventional method. Viathe NTC element 7 and/or 24 located in the temperature sensor 20 thetemperature of the control element surface can be determined, whichcorresponds to the interior air temperature.

Either information still does not take the air circulation (arrow) infront of the control element 30 into consideration. This determinationis made with the aid of heat element 5, 22 and the NTC 7, 24, and isbased on the heat retention of the mass of the foil 3, 25 and thedamping segment 8, 23, the materials of which are known. In a firstadaptive measurement at the NTC element 7, 24, the reaction of no aircirculation L_(ruh) is measured and stored as a control value. Thismeasurement can be determined during a factory installation of thesensor in a controlled environment (e.g. a no air flow environment). Themeasurement L_(ruh) may also be determined whenever the vehicle operatedand after a determination that there is no air flow, e.g., adetermination is made whether or not a fan of a heating and airconditioning system of a vehicle is operational.

The heat element 5, 22 is then provided with short pulses S_(normal) inrelatively long time intervals, through which the NTC 7, 24 is heated.From the difference of the step response in comparison with the reactionadaptively determined with the sensor with no air circulation L_(ruh),e.g., with the control value, air flow or no air flow is determined.

The damping of the impulse S_(normal) transmitted via theimpulse-damping segment 8, 23 thus provides information about the kindof air movement.

Experience has shown that depending on the air circulation, the stepresponse at the NTC element 7, 24 varies because the heat information ofthe heat resistor 5, 22 is dampened by circulating air. The curve of noair circulation L_(ruh) differs substantially from the curve ofcirculating air L_(bew), namely, in differing impulse width and heights,as illustrated in FIG. 4.

The knowledge of whether there is air circulation or not leads to aweighting of incident sun radiation and thus, the weighting of themeasured interior temperature. If the presence of air circulationL_(bew) is determined, it follows that the incident sun radiation in thepassenger area is higher than measured, whereby the measured valuecorresponds with the actual value of the interior temperature when noair circulation L_(ruh) is present.

Continuing with the method, and taking into consideration the determinedself-heating of the measuring area/control element 30, for example withthe additional aid of a NTC 31 in control element 30, a correct interiortemperature is determined with the help of the weighted values.

The weighted air circulation is thus entered as a correction value intothe interference values “sun” and “self-heating of control element” andultimately, into the control settings. Both values can be entered intothe control either separately or weighted as individual values.

Due to the sluggishness of unventilated temperature sensors, substantialtemperature changes in the passenger area can only be recorded with atime delay. The result of differing air flows on the sensor surface is avarying heat transmission resistance to the air in the passenger area.Substantial temperature changes are transmitted faster when aircirculation is present than when there is none (FIG. 5).

The measured air circulation in front of the control element 30 (and/orthe measuring area of the interior temperature in general) offers anadditional advantage. By recording an actual time constant, temperaturechanges can be detected early, which makes a quick adjustment of thesettings possible. In addition, with the aid of the step response, anexpected final value can be calculated. This also allows a systematicadjustment of the temperature settings.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are to beincluded within the scope of the following claims.

1. A method for determining an interior temperature based on a value forincident sun radiation recorded with a photo sensor and/or a surfacetemperature at a measuring area recorded with a temperature sensor,wherein air circulation in front of the measuring area is determined,which, is weighted as a variable heat-transmission resistance, and isentered as a correction value into the recorded incident sun radiation,wherein in a first measurement with the temperature sensor, a stepresponse of the temperature sensor at zero air circulation is taken andrecorded in response to a heat element being provided with a signal, andwherein from the difference of the step response as compared to a secondresponse the presence or absence of air circulation is determined, whichdetermination is utilized for determining the interior temperature basedon the correction value.
 2. The method according to claim 1, whereinwith air circulation present, the step response on the temperaturesensor shows a smaller impulse height and impulse width than a stepresponse when no air circulation is present.
 3. The method according toclaim 1, wherein the heat element is in close proximity of and thermallycoupled to the temperature sensor.
 4. The method according to claim 1,wherein the temperature sensor comprises: at least one sensor fordetermining the surface temperature of the measuring area, and the heatelement, which is thermally coupled with the at least one sensor.
 5. Themethod according to claim 4, wherein the thermal coupling is achievedvia a damping segment.
 6. The method according to claim 4, wherein thedamping segment is a foil with conduction tracks attached thereto. 7.The method according to claim 4, wherein the temperature sensor islocated in a housing and is arranged in an upper part of a foil, whichserves as a substrate for the temperature sensor, and into which areinjected at least the sensor for determining the surface temperature ofthe measuring area and the heat element, and wherein the housing isclosed off towards a lower portion thereof bottom with a castingcompound, with contact pins leading through it.
 8. The method accordingto claim 7, wherein the housing is made of infrared-permeable material,at least above an additional sensor for measuring the incident sunradiation, which is attached to the foil.
 9. The method according toclaim 6, wherein the temperature sensor is located in a housing, whereinthe foil is flexible and is folded and inserted into the housing,together with the attached sensor for determining the surfacetemperature of the measuring area and the heat element, and wherein foiltracks lead from the housing.
 10. The method according to claim 9,wherein an additional sensor for determining a self-heating of thecontrol element is attached to the foil in the housing, whereby thehousing is open in this area.
 11. The method according to claim 9,wherein the photo sensor measuring incident sun radiation is attached tothe foil, and that the housing has an infrared-light permeable areaaround the sensor.
 12. The method according to claim 11, wherein whenthe photo sensor is arranged below the foil, the foil is made ofinfrared-light permeable material in this area.
 13. The method accordingto claim 7, wherein the temperature sensor is manufactured utilizing MIDtechnology.
 14. The method according to claim 9, wherein the temperaturesensor is manufactured foil injection technology.
 15. The methodaccording to claim 1, wherein the heat element is a NTC.
 16. The methodaccording to claim 1, wherein the interior temperature is the interiortemperature of a motor vehicle.